Self-induced water intoxication, a condition frequently observed in psychiatric patients, almost always involves the symptom triad of psychosis, psychogenic polydipsia, and some form of inappropriate vasopressin secretion. Since angiotensin II (AII) is a potent stimulus for thirst and vasopressin release, we propose to test the hypothesis, based upon supportive preliminary data, that abnormalities of the renin-angiotensin system may be present in these patients that may contribute to self-induced water intoxication (SWI). The specific aims of this investigation will be to compare angiotensin II, renin activity, angiotensin-converting enzyme activity and aldosterone and vasopressin levels in plasma from (a) patients with chronic SWI and (b) patients with episodic SWI during and between acute episodes; (c) psychotic patients who have no history of SWI; and (d) non-psychotic psychiatric patients with no history of SWI. These parameters will also be examined in cerebrospinal fluid (CSF) from patients in these same groups and from Neurology Clinic outpatients, but only if CSF is being obtained for diagnostic purposes unrelated to the study. Angiotensin II, vasopressin and angiotensin I-generating activity (renin activity) will be measured by radio-immunoassay. We expect to establish the temporal relationship between renin-angiotensin system abnormalities and the presence of psychosis with or without psychogenic polydipsia, inappropriate levels of circulating vasopressin or SWI. In addition, we will determine, for the first time, the relationship between plasma AII and CSF AII in normal and psychotic subjects. The proposed studies may provide some clues about the pathophysiology of psychosis and specific psychotic disorders and may lead to more effective pharmacologic interventions for this syndrome which is associated with significant morbidity and mortality.